Fan blade



Patented-Oct. 5, 937

. UNITED/STATES PATENT "OFFICE This invention relates to a fan blade primarily intended for high speed heavy duty motors where a large volumeof air with a minimum amount of noise is-required, such as for ventilators or air coolers, although it is to be understood that the improvements are not so limited as they may be applied even to an airplane propeller.

It is particularly aimed to; provide such a construction as will be practically noiseless, as the bladesthereof are provided with a sloping leading edge with a graduated pickup and rounded rear edge and with a large center to prevent recirculation. 1

The more specific objects and advantages will become apparent from a consideration or the description 'following taken in connection with accompanying drawing illustrating an operative embodiment.

In-said drawing:,

Figure 1 is a view of the fan in plan;

Figure 2 is a cross sectional view taken on the line 2-40! Figure 1, and

Figure 3 is cross sectional detail tak n on the Cline 3-301 Figure 1.

Referring specifically to the drawing wherein like reference characters designate like or simiin parts; the fan'constituting my invention is generally of S-shape as shown at Hi. It .is in a single piece of sheet metal, adapted to be stamped '3 therefrom into the novel shape and it is pivoted or otherwise'secured to an-attaching'hub II as at l2, registering openings being provided through the hub and blade as at l3 and I4; and a set screw "preferably being carried by the hub to engage 35 the shaft which drives the Ian. In accordance-with-the invention, any desired 7 number of blades It, for instance two as shown, may be provided on the fan, and such blades.

' fan is relatively large so as to prevent-recircula from opposite sides have a sloping leading edge I portion at H, merging into a graduated pickup portion at it, and in turn-merging into a rounded rear or curved edge portion i9 (Figures 1 and 2). In addition, the central portion 20 of the tion of the air disturbed by the blades l8.

.As a result of the construction described, the fan will stir a large volume of air with a minimum amount of noise and the relatively large 10 center will stop any back flow so as to force all of the air forward under the action of the blades. The novel action is particularly apparent in a one-fourth horse-power motor. with aspeed of 1750 revolutions per minute.

While the device is primarily adapted for use in high speed heavy duty motors where a large volume of air with a minimum amount of noise is required, as in ventilators and air coolers, theprinciples may also be applied to advantage in airplane propellers. In such instance, the curved edge. l9 would be somewhat flexible so as to make the fan'blades self-adjusting for high and low altitudes.

Various changes may be resorted to within the 25 spirit and scope of the invention.

, I claim as my invention:-.-

A fan blade structure generally of $-shape inplan, providing i'an blades at thetwo extrem-' v ities thereof and a relatively large portion between the blades constructed and arranged to function for preventing recirculation of air, each' blade having a sloping leading edge portion extending inwardly beyond the rear edge portions, respectively, said rear edge portions being round-,-

' ed, substantially as described.-

L. WOOD. 

